OBJECTIVETo measure the frictions between FAS bracket and stainless steel wire under different two conditions, and compare two traditional self-ligating brackets.

METHODSFAS bracket was a new-style self-ligating bracket with a friction adjusting system (FAS) to adjust the friction as the wires slide in the bracket. Firstly, FAS bracket 20 times of original size was made, then the frictions were measured respectively made by the steel round wires of diameters 8.128 0 mm or the steel square wires in size of 9.1440 mm x 12.7000 mm. It was divided into two adjusting states, and used the same method to measure Damon III and SPEED bracket in 20 times of original size.

RESULTSWith the shim entirely drew in, all the frictions of the arch wire had no significant difference with the Damon III. When 8.1280 mm stainless steel round wire was used, SPEED bracket had no significant difference with FAS. When 9.1440 mm x 12.7000 mm square wire was used, they had significant difference (P < 0.05). On turning half a circle, all the frictions of the arch wire had significant difference with two tradition bracket (P < 0.01).

CONCLUSIONThe new-style FAS bracket can adjust the friction efficiently. Under no pressure state, the friction force is similar to Damon III. Under pressure state, FAS bracket locks the wires, and provides the sliding of wires.